You can use windows VSTi’s on linux using DSSI, although it can be a lot of effort to get it working, see https://forum.renoise.com/t/linux-how-to-use-native-windows-vsts/21240
You could try some native linux vst instruments, some work better than others: http://code.google.com/p/juced/downloads/list or try searching for ‘discodsp discovery’ or ‘loomer aspect’ for commercial linux vsts.
Some people have reported some success using the windows version of Renoise and their windows vsts in linux using wine, although personally I prefer to stick with the native linux stuff.